[mlangsdorf]

Historically, Britain and America both started re-arming around 1937-1938, which meant their war production was just becoming available by 1941 or so. Slightly more adroit German diplomacy, or another economic downtown, might have delayed rearmament another two years and might have resulted in a smaller rearmament program. Hypothetically, Britain could have gone into the war in France with half as many Hurricanes and with the factories still gearing up to produce Spitfires. The Chain Home radar stations may not have been built either, or as fully.

If Donitz had found better patrons among the German Navy, he might have gotten one of the Bismarcks removed from Plan Z in favor of another 25 U-boats.

Those two factors, plus an isolationist US not trading destroyers for bases, might have caused Britain to feel overwhelmed in the initial onslaught: U-boats prowling off the coasts while the Navy doesn't have nearly enough escorts to stop them, Luftwafte flying freely over England while the infrequent RAF interception results in more dead RAF pilots than downed German planes. Churchill would want to fight to the last, but others in the government might decide that things aren't going to get better quickly enough, and negotiate a "peace with honor" that lets England keep most of the Empire and gives Germany a free hand in Russia.